The NRC will organize an ad hoc study to determine whether a proposed NASA plan for a U.S. hardware contribution to the European Space Agency (ESA) Euclid mission, in exchange for U.S. membership on the Euclid Science Team and science data access, is a viable part of an overall strategy to pursue the science goals (dark energy measurements, exoplanet detection, and infrared survey science) of the New Worlds, New Horizons report’s top-ranked, large-scale, space-based priority: the Wide Field InfraRed Survey Telescope (WFIRST).